Burner controlling apparatus



D. G. TAYLOR ET AL BURNER CONTROLLING APPARATUS May 23,1933.

Filed Aug. 11, 1950 PasT-m/v/rmy PlPt-la/vlrloly WV 3 I NW g .3

TA'ARMAL s/mery .srr.

WAKE

Inventors DAN/EL 6. 7JqY/ oe EENES MM/LLE/Z 14 TTOENE' Patented May 23, 1933 UNITED STATES PATENT OFFICE DANIELLG. TAYLOR AND ERNEST M. MILLER, OF M INNEAPOLIS, MINNESOTA, ASSIGN- ORS TO MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, OF MINNEAPOLIS, MIN- NESOTA, A CORPORATION OF DELAWARE BURNER CONTROLLING APPARATUS Application filed August 11, 1930. Serial No. 474,544.

This invention relates to improvements in automatic control mechanisms for heating plants, and has amongits objects; to provide means for initiating and timing two ignition periods, one before and one after burner motor activation to provide a delayed re-trial re-ignition period after flame .failure due, to causes other than a call for less heat by the room thermostat; to time this delay period by cooling motion of a thermal element; to provide among other things a thermally operable device of the diflerential type which when in thermal equilibrium, conditions the control apparatus for'starting when the room thermostat calls for heat, and which thermally operable device is adapted to be moved a result of application of heat to close and, initiate motor operation, and in'which upon application of heat from a different source the starting contact, (which has closed'as a result of thermal equilibrium) is opened to such a degree that i a re-start is impossible except at the end of a timed period which is determined by the cooling' motion of the timing element; and genorally to provide means for automatically controlling a burner apparatus adapted to time pre and post ignition periods, and automatically stop the apparatus if 'flame is not produced, and lock it against automatic re-start.

Features of the invention include all of the circuit arrangements shown'in the drawing and their equivalents, along with those broader aspects of the invention which relate to the automatic control including a preignition period, and a post-ignition period or continuation of ignition for a predetermined time after ignition is produced, and the prevention of a rc-ignition operation, ex

' cept at the ,end of a predetermined interval,

after flame extingu-ishmentfrom any cause, except a call forless heat by the controlling temperature-responsive device, or its equiva-" lent.v

'Features, objects and advantages of the invention will appear in the description of the drawing, forming a part of this application, and in said drawing Figure 1 is a diagrammatic view of one embodiment of the invention, which includes a thermal safety switch as a means for locking the apparatus against further operation,

if flame is not produced at the end of the pre-.

determined ignition period;

Figure 2 is a fragmentary diagram showing a portion of the'system and its modified arrangement of circuits; due to omission of the thermal safety switch or timing mechamsm.

In the drawing, numerals 6 and 7 indicate themain power lines. Numeral 5 indicates the secondary of a transformer, the primary of which is connected across the lines at 6 and 7 1 indicates a burner motor, and it is assumed that a suitable burner is controlled thereby, although not shown. Numeral 2 indicates what is herein termed a post-igni tion means. Numeral 3 indicates what is herein termed a pre-ignition means. WRB represent the contacts. of a room thermostat. Elements 8 and 24 represent a thermal safety switch which is adapted to open if flame is,

not been shown. There are three relays or equivalent devices employed, and they are respectively referred to as N o. 1, No. 2 and N o. 3. Their coils are respectively indicated at 11, 12 and 13. Relay No. 1 controls four contacts, 14, 15, 16, 17, and its closure, among other things, results in energization of preignition means 3. Relay N0. 2 controls three contacts, 18, 19, 20 and its energization results, among other things, in energization of motor 1 and post-ignition means 2. Energization of relay No. 2 is brought about by the motion of a thermal element (28-29 of the difl'erential type) to. switch closing position, due to application of heat by an electrically operable heating element 26 which is inthe starting and holding circuits the thermal device is shunted, and the thermal element cools, 'openmg the contact which was previously closed to obtain energization of relay No. 2. Relay No. 3 is controlled by a device 10 which closes a contact if flame is produced at the burner, and the relay in turn controls 3 contacts. Before energization, one contact controlled by this relay is closed and is in the starting circuit for No. 1 relay. On energization of No. 3 relay the thermal timer switch receives heat by means of a second electrically operable heating device 25, and begins a movement, at the end of which, the holding circuit for relay No. 1 will be broken. Thls relay No. 3 also controls a contact which shunts out the safety timer heating coil 24. The energization of No. 3 results in the de-energization of both ignition means 2 and 3, and continued operation of the burner motor 1. This operation normally takes place until the room thermostat opens its contacts BR, WR, conditioning the apparatus for a normal start including a trial ignition period, on a call for; more heat at the room thermostat.

A more detailed description of the arrangement and functions of the parts, is given there below under the heading Operation.

Operation 26, coil 11 of relay No. 1, to the other side of the secondary 5. Relay 1 is now energized and holding contact 14 is closed, contact 15 which controls energization of relay No. 2 is closed, contact 16 closes and the preignition means 3 is energized, and contact 1 is closed to condition the post-i ition means for energization on closure 0 relay No. 2. Heating coil '26 is now receiving current, and the elements 2928 are moving in a direction of arrow G, to close contact 40 at the end of a predetermined time, which is the pre-ignition period. o v I 0n closure of contact 40 relay No. 2 is energized through the following circuit: one side of secondary 5, thermal switch 8, W-R, contact 14 of relay N0. 1, contacts 34, 40 of the timer switch, contact 15 of relay No. 1, heatingv coil 24 of the'thermal safety switch, coil 12 of relay No. 2 to the opposite side of secondary 5. On closure of relay 0. 2, a holding circuit for No. 2 relay is made as follows: 5, 8, W-R, contact 18 of relay No. 2, contact 15 of relay No. 1, coil 24, 12, to 5. Contact 19 also closes and shunts out timer switch coil 26.

The startin and holding circuits for No. 2

pass through t e coil 24 of the thermal safety.

of a predetermined period the whole apparatus will be de-energized and the safety switch 8 will lock the devicein the usual well known manner. Activation of the igniter for a timed period before feeding fuel is particularly desirable when ignition means of the hot wire or glow bar type is used. This type of ignition means isincapabIe of igniting oil until the igniter becomes red hot. However, when the glow bar is repeatedly heated tosuch high temperature it deteriorates very quickly whereas if it is only heated sufficiently to cause it to act as a vaporizer and not as an igniter, its life is prolonged. The glow bar is used for vaporizing the oil preparatory to ignition. The pre-ignition means is first energized and then the motor and post-ignition means 2 are energized simultaneously while the ignition means ,3 continues to be active. A predetermined time after flame is established, and responsive to any suitable combustion responsive device or devices, both ignition means 2 and 3 are simultaneously de-energized.

- The present invention includes a timed operation of i ition before oil is delivered (pre-ignition and a timed operation of ignition (post-ignition period) after flame is produced, along with various safety and recycling features. In the present disclosure,

low bar and spark ignition can be used, if desired. If another type of ignition is desired, wherein one devicewill properly perform the igniting function, it is within the scope of-this invention to eliminate the supplemental ignition means 2.

Assuming that flame is produced before the safety switch 8 opens, relay No. 3 will be energiz'ed as the result of closing of contact 10 of the pyrostat or flame responsive device. This closure results in energization of relay No. 3 and post-ignition timer coil 25. On energization of relay No. 3 the starting contact 23 for No. 1 is opened, and contact 21 is closed which shunts out the coil 24 of the thermal safety switch 8 (it is to be noted that the holding circuits are always first to be made, then the starting circuits). The holding circuit for No. 2 now passes through contacts-21 and 22 controlled by relay No. 3 and through the holding contact 18 for No. 2.

is broken at 34. Relay No. 1 falls out and the bnergized, this interval being provided so that in case of flame failure, during normal operation, there will be time allowed for dissipation ofexplosive gases before starting contact 23 is closed and therefore before recycling operation and reenergization of relay No.

1 can be had. Thus far, the normal operation only has been described in which flame is continuous until thereis a call for less heat at which time the entire apparatus is shut down until a call for more heat takes place. However, in case no flame is produced, during an ignition period, switch 8 will be opened and locked, and theapparatus cannot function automatically until after inspection and repair. v

The starting circuit for ,No. 1 relay is through the thermal safety switch 8, also through contact 23 of the flame responsive relay No. 3, through the time switch (contact and through the pre-ignition timer coil 26. The holding circuit for No. 1 relay is also through the thermal safety switch 8 but contact 35 which is in the starting circuit for No. 1 relay, is shunted out. The holding cirformer.

cuit for No. 1 relay is as follows: one side of the transformer of safety switch 8, W, R, to contact 14 of relay No. 1, contact 34, 33, 32, 28, 29, 26, 11 to opposite side of the trans- This contact 35 is controlled by the thermal timing element 28, and is held operrwhile flame is present (due to the heating action of element 25). "This. contact closes to permit re trial ignition after flame extinguishment onlyat the end of a timed period (controlled by the cooling motion of 28-29), to allow for dissipation of any ex plosive mixture in the fire box.

The starting circuit for No.' 2 relay may be through either one of two paths. First, from source 5, switch 8, WBR, contact 23 40, contact 15 of relay No. 1, heating coil 24 of thermal safety switch, to coil 12 of relay No, 2, thence to source 5. Or, second, source 5, switch 8, WR, contact-14 of relay No. 1, contacts 3440, contact 15 'of relay No. 1, 24, 12, to source 5. 1

After closure of No. 2, heating coil 26.is shunted out due to closure of contact 19 of relay No. 2, through the following circuit: 5,8,WR, 14,34,2s,29, 19 to 11, to 5. Contact 18 of relay N0. 2 is closed and is adapted to maintain the circuit of relay No. 2 closed after 'No. 1 is opened, provided No. 3 is pendently of contacts 40-34. This circuit On energization of No. 2 relay, the motor and post-ignition are energized.

On energization of No. 3 relay due to production of flame'and due to closure of flame switch contact 10, contacts 21 and 22 are closed. Contact 21 establishes a holding circuit for relay No. 2 which does not include the coil 24. In other words, the closure of contact 21'shunts out coil 24. At this time a holding circuit at contact 22 is established for No. 2 relay which is independent of contact 34, which contact will be opened at the end of a predetermined interval after the closure of N o. 3 relay. The holding circuit for No. 2.can now be traced from 5 through 8, W, R, 18, 22, 21 to 5;

The thermally operable timer switch d'ia grammatically indicated herein as composed of two sets of bi-metallic elements 28-29, may be of any preferred form. As a matter of fact the device used is somewhat more complicated than thatdiagrammatic'ally illustrated. Any equivalent device may be used,

energization by another heater asresult of closure of the flame responsive device, moves v the element to open the contacts 3534. It will be noted that when the elements 28 and 29 are in thermal equilibrium, contacts 34 35 are closed and contact -40 open. Upon application of heat at 26 element 29 warps in the direction shown by arrow G, and contact 40 is closed at the end of a predetermined time. When 26 is de-energized as result of closure ofNo. 2 relay, on cooling of element 29 the elements 2829 move in the direction of the arrow H in an opposite direction to ,open the contact 40, and on application of heat throughelement 25 element 28 warps and this motion is continued in the same direction and at the end of a timed period contacts 3534are opened. Heating of 25 is, however, continued beyond this point and in fact continues aslong as flame is present and as long as contact 10 is closed. It results that during normal operation or flame period of the burner, the elements 3233 are held in spaced relation to contacts 34-35 as the result of continued application of heat.

Therefore, on flame failure and resultant deenergization of coil 25, contacts 34 and 35 will not be again made until after a predetermined time. interval obtained by a cooling movement of element 28 in direction of the arrow G. Thus, before a rte-start or retrial ignition period can be initiated, sufficient time elapses for the dissipation of explosive gases from the fire box, by natural draft, or otherwise.

Thus means is provided (relay No. 1 or its equivalent) which is energized on a call for heat and closes the pre-ignition circuit, as

05 is as follows: 5, 8, W, R, 18, 22, 21, 12 to 5." well as'a contact which isin the post ignition circuit. This relay energization is made through a circuit which includes thermal safety switch 8, a contact 23 of relay No. 3 (closed when flame is absent), timer switch contact 35 (closed when blade is in equilibrium) and the pre-ignition timer coil 26. No. 2 relay controls the motor 1 and postignition means 2, and energizes when the timer contact 40 closes at the end of a preignition period as determined by the heating motion of the thermal element 29 by timer coil 26. No. 2 relay is energized by a circuit which passes through the thermal safety switch 8, VVR, contact 14 of relay No. 1, and timer switch, contacts 34, 40, contact 15, heater 24, and coil 12, or by circuit 8, WEB, 23, 35, 40, 15, 24 to 12. When No. 2 relay energizes, it establishes a holding circuit for itself independently of timer switch contact 40, as follows: 8, "WR, 18, 15, 24, 12 to 5.

It should be noted that one timer switch contact 40 is closed by heating motion initiated by a call for heat, and that the other two timer switch contacts 35, 34 are successively opened as a result of heating motion initiated by production of flame. It should further be noted that contacts 35, 34 are maintained in open posit-ion as a result of continued application of heat (through coil 25) while the burner is producing flame. On flame failure, some appreciable amount of time is therefore required for these last two contacts to close, as result of a cooling motion to control element 28.

It is conceivable that a circuit which falls Within the purview of this invention, may be one in which the thermal safety'switch 8 and its timer coil 24 are omitted. In this instance, see Fig. 2, there is no necessity for shunting out the coil 24 and therefore contact 21 is omitted. There will be no change in the circuit for relay No. 1, but when relay No. 3 is energized, the holding circuit for No. 2 relay will be only through contact 18 of relay No. 2 and contact 21 of relay No. 3. This explanation is made, because it is conceivable that the invention herein may be applied to systems in which it is unnecessary to .provide an electro-thermally operable safety switch. which locks the system against automatic operation if ignition is unsuccessful.

Reverting the timing feature:

In the first instance a heating motion closes one of the timer switch contacts (40). Tn another instance the heating motion breaks two of these contacts, (35, 34) and continued heating motion of element 28 in direction of arrow H, separates the contact or contacts, so that closure of these contacts for a restart is timed by a cooling motion, making it impossible to energize the ignition means until after a predetermined time, at the end of which there will no longer be sufficient residual fuel in the fire box to cause explosion as a result of re-trialignition.

In this device every low voltage circuit passes through the thermal safety switch 8. It is also to be noted that on a call for heat the starting circuit passes through elements WRB of the room thermostat. However, if other relays are employed, as in the present case, contacts WR only of the room thermostat are used for controlling the starting as well as the holding circuits of these additional devices.

It is again to be noted that in this device, when flame fails while the room thermostat is calling for heat, the motor is shut down immediately that the flame-operated switch 10 opens; a very important feature. Moreover, re-trial ignition cannot take place until explosive gases are dissipated; another important feature.

In certain controls heretofore used, after a flame failure, the burner would not perform a trial ignition or starting operation or cycle, but the burner would simply opcrate for about two minutes, Without ignition and with no flame, and with oil being supplied, and then the device would be locked against further automatic operation. The same thing would happen if flame was cX-' tinguished immediately after ignition was discontinued at the end of the trial ignition period. This arrangement had certain disadvantages. IJnder these conditions the refractory was hot and on reestablishment of the ignition, explosion would take place. In the present device, it is impossible to re-start the apparatus, after flame failure while the room thermostat is calling for heat until after a timed interval during which dangerous explosive mixtures are dissipated by the natural draft of the furnace.

We claim as our invention:

1. In combination, a burner apparatus including a burner and burner motor and ignition means, and means adapted to control the motor and ignition means to activate said ignition means for a predetermined time before burner motor activation, and then con tinue ignition means operation, said means including a thermally resposive switch of the differential type adapted when in thermal equilibrium to permit activation of said ignition means on a call for heat, and means operable after ignition activation to move said thermal element to close a circuit which results in activation of the motor and continued activation of said ignition means, and means responsive to production of flame at the burner operable after burner activation to initiate a timed movement of said thermal switch at the end of which said ignition means is de-activated, and motor activation continued, and re-activation of said ignition means is prevented until after a predetermined interval of time, following flame failure, after successful ignition.

2, In combination, a burner apparatus including a burner and burner motor, preignition means, post-ignition means and means adapted to control the motor and ignition means to activate said pre-ignition means for a predetermined time before burner motor activation, and then activate said post-ignition means and maintain activation ofsaid pre-ignition means, said means including a thermally responsive switch of the differential type adapted when in thermal equilibrium to permit activation of said preignition means on a call for heat, and means operable on pre-ignition activation to move said thermal element to close a circuit, which results in activation of said post-ignition means and motor, and means responsive to production of flame for initiating a timed movement of said thermal element at the end of which both ignition means are deactivated, and prevent re-activation of said ignition means until after a predetermined interval of time, following flame failure.

3. In combination, a burner apparatus and a burner motor, ignition means, means adapted to activate said ignition means for a predetermined period of time before motor activation, means adapted to activate the motor at the end of said timed period,and to continue ignition means activation thereafter, and means operative as a result of production of flame to effect de-activation of said ignition means at the end of a second timed period and to thereafter continue motor activation. a 1

4;. In combination, a burner apparatus and a burner motor, ignition means, means adapted to activate said ignition means for a predetermined period of time beforemotor activation, means adapted toactivate the motor at the end of said timed period, and to continue ignition means activation thereafter, and -means operative as a result of production of flame to effect de-activation of said ignition means at the end of a second timed period thereafter and to continue motor activation, and to prevent re-activation of the ignition activating means for a predetermined length of time after flame failure following successful combustion. v

5. In combination a burner apparatus and a burner motor, first and second ignition means, means adapted to activate the first ignition means for a predetermined "timed period before motor activation, means adapted to activate said motor at the end of said time period, and to activate said second ignition means and thereafter continue'activa-W tion of both ignition means, and motor, and means operative as a result of production of ,flame and at the end of a time period, to effect de-activation of both ignition means butcontinue motor activation.

- timer switch,

6. In combination a burner apparatus and a burner motor, first and second ignition means, means adapted to activate the first ignition means for a predetermined timed period before motor activatiommeans adapted to activate said motor at the end of said time period, and to activate said second ignition means and thereafter continue activation i of both ignition means and motor, and means operative after production, of flame and at the end of a time period after flame production to effect fie-activation of both ignition means but continue motor activation, andalso.

operative to prevent re-activation of the first mentioned means for a predetermined length of time after flame failure following successful combustion.

7. A device of the class described including a burner and a burner motor, ignition means, means adapted to activate said 1gI11l710I1 means for a predetermined time before motor activation, means adapted to activate said means, a room thermostat, an ignition timer switch controlling first, second and third contacts, first and second electrically operable means for effecting motion of the timer switch, a first relay operable when energized to energize the ignition means, a second relay operable when energized to energize the motor, a third relay, means operable to energize said third relay as the result of production of flame at the burner;v a starting circuit for f the first relayv including therein the room thermostat, a contact ofthe third relay which -is closed when the relay is de-energized, the

first contact of said ignition timer switch, and said first timer switch motion effecting means; a holding circuit for said first relay, having therein said room thermostat, a holding contact controlled by said first relay, the

second contact of the timerswitch, and said' 7 first timer switch motion effecting means;

said first timerswitch motion effecting means maintaining closed the first and second timer switch contacts and closing the third timer switch contact; a starting circuit for said second relay, having therein said room thermostat, said holding contact of the first, relay, the second and third contacts. of said and a second contact of the first relay; said second relay on energization shunting out said first timer switch motion efiecting means; a holding circuit for said second relay, which has therein said thermostat, a holding contact controlled by said second relay, and said second contact controlled by said first relay; said third relay being in a circuit through said second timer switch motion effecting means, and having contacts which upon energization of the relay estab lish a holding circuit for the second relay through said room thermostat, which circuit is independent of the contacts controlled by the first relay, said second timer switch motion effecting means when energized causing opening of said first and second timer switch contacts.

In witness whereof, we have hereunto set our hands this 30th day of July 1930.

DANIEL G. TAYLOR. ERNEST M. MILLER. 

